1. Field of the Invention
The present invention relates to a scroll hydraulic machine used as a compressor or an expansion device. The present application is based on Japanese Patent Application No. Hei 9-199160, the contents of which are incorporated herein by reference.
2. Description of Related Art
A vertical cross-section of a conventional scroll compressor is shown in FIG. 8. In FIG. 8, reference numeral 1 denotes a housing comprising a cup-shaped body 2 and a front housing 6 attached to the cup-shaped body 2 by a bolt (not shown). A fixed scroll 10 meshing with a swirling scroll 14 are disposed within the housing 1. The swirling scroll 14 performs a rotational swirling motion, and this rotational swirling motion is controlled by an Oldham ring 26.
In FIG. 9, the Oldham ring 26 comprises a ring 26c, a pair of swirling keys 26a, and a pair of fixed keys 26b. Each swirling key 26a engages so as to freely slide in the direction of arrow A in a pair of a key groove 41 bored into the outer surface of the end plate 15 of the swirling scroll 14. Each fixed key 26b engages so as to freely slide in the direction of arrow B in a key groove 42 formed along the thrust bearing 36 and a key groove 43 bored into the inner end surface of the front housing 6.
In a conventional scroll compressor, the front housing 6 and the swirling scroll 14 are made of an aluminum alloy, and the Oldham ring 26 is made of a ferrous alloy. Because the ability of the aluminum alloy and the ferrous alloy to slide over one another deteriorates, there arises the problem that abrasion or seizure occur between the swirling key 26a and the fixed key 26b of the Oldham ring 26, and their a key groove 41 and 43, damaging the Oldham ring 26.
In addition, the sliding surfaces of the swirling key 26a and the fixed key 26b of the Oldham ring 26 and their key grooves 41 and 43 are lubricated by an aerosol oil incorporated in the gas drawn into the suction chamber 28. However, when the compressor is stopped for long periods of time, the liquid refrigerant clinging to the inside of the housing wash out the oil on the sliding surfaces, and due to this, when the compressor is restarted, abrasion or seizure occur on the sliding surfaces.